Electrolytic cell including vertical hollow anodes with deflector panels diverging upwardly from each anode

ABSTRACT

ANODES FOR ELECTROLYSIS CELLS FOR PRODUCING A GAS BY ELECTROLYSIS COMPRISE VERTICALLY DISPOSED HOLLOW METAL BOXES OPEN AT THEIR LOWER AND UPPER ENDS AND HAVING TWO OPPOSITE PARALLEL METAL WALLS ARRANGED FACING ONE ANOTHER. THESE WALLS ARE SURMOUNTED BY TWO DEFLECTOR PANELS WHICH INCLINE OUTWARDLY AWAY FROM ONE ANOTHER SO AS TO DIVERGE UPWARDLY. THE DEFLECTOR PANELS MWAY BE INTEGRAL WITH THE WALLS OR MAY BE SEPARATE MEMBERS SECIRED TO THE UPPER PORTIONS OF THE WALLS.

Feb. 5, 1974 U, GMCOPELL. ETA; 3,790,465

ELECTROLYTIC CELL INCLUDING VERTICAL HOLLOW ANODES WITH DEFLECTOR PANELS DIVERGING UPWARDLY FROMEACH ANODE Filed Dec. 6. 1972 5 Sheets-Sheet 1 Fig. 1

Feb. 5, 1974 u. GIACOPELLI ETAL, 3,790,455

ELECTROLYTIC CELL INCLUDING VERTICAL HOLLOW ANODES WITH DEFLECTOR PANELS DIVERGING UPWARDLY FROM EACH ANODE Filed Dec. 6. 1972 I 5 Sheets-Sheet 2 Feb. 5, 1974 GlACOPELLl ETAL 3,790,465

ELECTROLYTIC CELL INCLUDING VERTICAL HOLLOW ANODES WITH DEFLECTCR PANELS DIVERGING UPWARDLY FROM EACH ANODE Filed Dec. 6 1972 3 Sheets-Sheet 1 FIG. 3

United States Patent O 3,790,465 ELECTROLYTIC CELL INCLUDING VERTICAL HOLLOW ANODES WITH DEFLECTOR PANELS DIVERGING UPWARDLY FROM EACH ANODE Umberto Giacopelli, Rosignano Solvay, Livorno, Italy, assignor to Solvay & Cie, Brussels, Belgium Filed Dec. 6, 1972, Ser. No, 312,706 Claims priority, application France, Dec. 6, 1971, 7143789 Int. Cl. 801k 3/10 US. Cl. 204--266 9 Claims ABSTRACT OF THE DISCLOSURE Anodes for electrolysis cells for producing a gas by electrolysis comprise vertically disposed hollow metal boxes open at their lower and upper ends and having two opposite parallel metal walls arranged facing one another. These walls are surmounted by two deflector panels which incline outwardly away from one another so as to diverge upwardly. The deflector panels may be integral with the walls or may be separate members secured to the upper portions of the walls.

The present invention relates to improvements in anodes of cells for the electrolysis of solutions in which a gas is recovered at the electrodes, particularly for the electrolysis of brines of alkali metal halides such as sodium chloride.

The invention relates more particularly to a hollow metal anode for a cell of this type, this anode being open at its upper and lower ends and comprises two more or less vertical walls arranged facing one another.

In the known cells with vertical electrodes in which a gas, for example chlorine, is produced at the electrodes, one is generally restricted in the choice of the height of the electrodes. Electrodes which are too high in fact encumber the release of the gas towards the top of the cell, with the unfavorable result of a decrease in the current yield and an increase in the voltage.

The use of hollow metal anodes, open at their upper and lower ends, as described in British Pat. 1,087,529 of Nov. 4, 1965, in the name of Murgatroyds Salt and Chemical Company Limited, enables one to overcome this drawback by providing a descending circulation of the anolyte between the vertical walls of each anode, and an ascending circulation of the anolyte in the anode/ cathode spaces. Experience has shown, however, that in order to provide a correct circulation of the anolyte in these known cells with hollow anodes, it is necessary to provide for a suflicient distance between the two vertical walls of the anodes, on the one hand, and a sufncient width of the anode/cathode spaces on the other. The result of this is the disadvantage of a considerable size of the cell and an increase in the electrical resistance of the electrolyte between the electrodes.

The present invention overcomes these drawbacks. For this purpose, in the anode according to the invention the two above-mentioned vertical walls are surmounted by two deflector panels inclined towards the outside so as to diverge upwards.

It has been found that, all other things being equal, in a cell equipped with anodes according to the invention, the presence of the above-mentioned deflector panels has the eifect of increasing the ascending speed of the anolyte and of the gas in the anode/ cathode spaces, and facilitating the subsequent separation of the gas and the anolyte in the zone of the cell situated above these deflector panels.

The anode according to the invention thus has the considerable advantage of being able to provide a smaller distance between its vertical walls; it also permits a decrease in the width of the anode/cathode spaces of the cells.

The invention also relates to a cell for the electrolysis of solutions where a gas is recovered at the electrodes, particularly for the electrolysis of solutions of alkali metal halides, this cell comprising, in a tank, a series of more or less vertical hollow metal anodes which are open at their upper and lower ends, alternating with more or less vertical cathodes.

In the cell according to the invention, each anode is surmounted by two deflector panels facing obliquely upwards and towards the two cathodes arranged on either side of the said anode. Preferably the distance between the top ends of two deflector panels which belong to two successive anodes and which are inclined towards the cathode situated between these two anodes is at most equal to double the anode/ cathode distance.

In a particular form of embodiment of the cell according to the invention, each of the anodes may comprise two plates made of a metal of the titanium group arranged facing one another and covered on at least a part of their surface facing the outside with a layer comprising a metal or a compound of a metal of the platinum group, these two plates being fixed transversely to a side wall of the tank of the cell above the bottom of the said tank. The two above-mentioned plates of each anode are also connected to one another by a plate extending along their edge which is furthest from the above-mentioned side wall of the tank, so as to form a box which is open at its upper and lower ends.

Special features and details of the invention will appear from the description which follows of the attached drawings which represent, solely by way of example, a few forms of embodiment of the anode and the cell according to the invention.

FIG. 1 shows in perspective, with a partial cut-away, a particular form of embodiment of the anode according to the invention;

FIG. 2 shows partly in transverse vertical section a form of embodiment according to the invention of a digphragm cell for the electrolysis of a sodium chloride nne;

FIG. 3 is a section along the planes III-IH of FIG. 2.

In these figures the same reference numbers designate identical elements.

FIG. 1 shows a hollow metal anode designated generally by the reference number 1. This anode 1 comprises 2 metal walls 2 and 3, for example of titanium, which are more or less vertical and arranged facing one another. The surfaces of these walls facing the outside are covered, at least in part, by a metal or a compound of a metal of the platinum group. U sections 4 are fixed, for example by welding, vertically to the walls 2 and 3 so as to form with these walls an anode in the form of a box which is open at its top end 5 and bottom end 6. Drillings 7 are arranged along the vertical edges of the walls 2 and 3 for the passage of bolts for fixing the anode on to an anode support, in a manner which will be described below.

According to the invention the walls 2 and 3 are each surmounted by a deflector panel 8 or 9 respectively. These deflector panels 8 and 9 are inclined towards the outside of the anode so as to diverge upwards. They are extended towards the bottom by a more or less vertical wing 10 which makes it possible to fix them to the walls 2 and 3 by means of bolts or screws 11.

The deflector panels 8 and 9 may be made of an insulating material for example chlorinated polyvinyl chloride.

As a variant, the deflector panels 8 and 9 may be bent so that each has an upper wing 12 of a smaller inclination or more or less vertical.

According to another variant, not shown in the drawings, of the anode of FIG. 1, the deflector panels 8 and 9 are joined to one another by struts or by transverse walls so as to form a rigid assembly. The latter may thus be held on the walls 2 and 3 of the anode by gripping the wings between these walls so that it is possible to do away with the bolts 11.

In a modified form of embodiment of the anode ac cording to the invention, not shown in the drawings, the deflector panels 8 and 9 form an integral part of the walls 2 and 3, of which they constitute extensions.

In this modified form of embodiment the deflector panels 8 and 9 may be covered at least partly on their surface facing the outside with a conducting layer made of a metal or a compound of a metal of the platinum group so as to increase the active surface of the anodes.

FIGS. 2 and 3 shoW a particular form of embodiment of a chlorine cell in accordance with the invention. This cell comprises in a known manner a tank 13 closed by a lid 14. The middle zone of the tank 13 consists of a metal U section 15 supporting an assembly of more or less vertical cathode pockets 16 covered with a diaphragm 17. These cathode pockets 16 communicate on the one hand with the lower tubulure 18 for the evacuation of the cathode alkali liquor and on the other hand with an upper tubulure 19 for the evacuation of the hydrogen given off at the cathodes 16.

Between the cathode pockets 16 there are arranged anodes 1 which are more or less vertical. These anodes 1 are analogous to that described above and shown in FIG. 1. They are fixed perpendicularly to an anode support 21 which serves as a wall by means of bolts 22 passing through holes 7 in the plates 2 and 3. The anode support 21 is fixed to the U section 15 by bolts 24 and nuts 23 made of an insulating material, with a sealing joint 25 inserted between them.

The lid 14 communicates with a. tubulure, not shown in the drawing, for the admission of brine and with a tubulure, not shown in the drawing, for the evacuation of the chlorine evolved at the anodes 1.

Angle-bars 27 connected with one another by tie-rods 28 hermetically hold the U section 15 and the anode support 21 between the lid 14 and the bottom 29 of the tank 13, with sealing joints 30 placed in between.

The anodes 1 with which the cell of FIGS. 2 and 3 is equipped are each surmounted according to the invention by two deflector panels 8 and 9 analogous to those described above and connected with one another by transverse walls 31 and struts 32. These deflector panels 8 and 9 of each anode 1 are directed obliquely upwards and towards the two cathodes 16 arranged on either side of the said anode.

These deflector panels may be shaped in such a way that two panels 8 and 9 which belong to two successive anodes 1 respectively and which are directed simultaneously towards the cathode 16 arranged between these two anodes have their upper ends 33 and 34 at a distance from one another which is at most equal to double the distance between two neighboring electrodes.

During the operation of the cell represented in FIGS. 2 and 3, the gas given oif at the anodes 1, in this case chlorine, rises in the anode/cathode spaces 35 and entrains some anolyte with it. On contact with the deflector panels 8 and 9 the gas bubbles undergo a coalescence, which accelerates their ascending movement. In the zone 36 of the lid 14, situated above the deflector panels 8 and 9, the ascending movement of the gas and of the anolyte is slowed down, which causes a separation of the gas and the anolyte. The anolyte is collected between the two walls 2 and 3 of each anode 1, whence it falls to the bottom of the tank 13 and it is then recycled into the anode/ cathode spaces 35.

Experience has shown that, all other things being equal, a cell according to the invention whose anodes are surmounted by deflectors offers improved performances of operation as compared with an analogous cell whose anodes do not possess such deflectors. In particular, the use according to the invention of deflectors above hollow anodes makes it possible, for the same size of cell, to reduce the anode/cathode tension and to increase the current density. This is particularly significant for cells in which the distance between the two walls 2 and 3 of the anodes is less than 20 mm. Reciprocally, for equal performances, the use according to the invention of deflectors above the anodes makes it possible to reduce the distance between the two walls of each anode and consequently the overall size of the cell.

The present invention is not restricted to the forms of embodiment described above. Numerous modifications may be made therein without thereby falling outside the framework of the following claims.

What I claim and desire to secure by Letters Patent is:

1. In an electrolytic cell for the electrolysis of solutions with the recovery of a gas at the electrodes, said cell having generally vertically disposed anodes alternating with cathodes, the improvement comprising said anodes being open at their lower and upper ends and comprising two generally vertical walls arranged facing one another, and two deflector panels extending upward from said walls and inclined outwardly from one another so that said deflector panels diverge upwardly.

2. The construction according to claim 1, in which said cell is a diaphragm cell for the electrolysis of brines of alkali metal halides.

3. The construction in accordance with claim 1, in which the distance between the upper edges of two said deflector panels belonging to successive anodes is at most equal to twice the distance between neighboring electrodes.

4. The construction in accordance with claim 1, in which said deflector panels have approximately vertical upper edge portions.

5. The construction in accordance with claim 1, in which said deflector panels are separated members secured on upper portions of said walls of said anodes.

6. The construction in accordance with claim 5, in which said deflector panels are of insulating material.

7. The construction in accordance with claim 1, in which said walls are of a metal of the titanium group covered over at least a part of their outer surfaces with a layer of material selected from the group consisting of metals of the platinum group and compounds of metals of the platinum group.

8. The construction in accordance with claim 7, in which said deflector panels form integral parts of said walls of which they constitute extensions.

9. The construction in accordance with claim 8, in which said deflector panels are covered on at least part of their outwardly facing surfaces with a layer of mate rial selected from the group consisting of metals of the platinum group and compounds of metals of the platinum group.

References Cited UNITED STATES PATENTS 1,420,037 6/1922 Harris 204-289 GERALD L. KAPLAN, Primary Examiner W. I. SOLOMON, Assistant Examiner US. Cl. X.R. 

